Heat sensitive device



Dec. 7, 1943.

s. G. ISSERSTEDT 2,336,400

'HEAT SENSITIVE DEVICE v Filed Jan. 17, 1942 INVENTOR. icgfriel lssczx s'i-eai- Patented Dec. 7, 1943 UNITED STATES PATENT OFFICE HEAT SENSITIVE DEVICE Siegfried G. Isserstedt, Minneapolis, Minn, as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application January 17, 1942, Serial No. 427,201

13 Claims.

and which has a wall through which radiant heat first member of a form having a substantially cirmay freely pass. A heat absorbing means is located in the chamber in order to absorb radiant the construction strength, and these walls will absorb a substantial amount of heat and therefore have a material eil'ect in additionally heating the air in the chamber. Therefore when the amount of radiant heat passing into the chamber has been materially reduced or entirely cut off, the residual heat in the walls of the device will continue to heat the air and thereby prevent it from contracting and reducing vthe pressure within the chamber an amount corresponding to the actual amount of radiant heat which the chamber is receiving.

It is therefore one of the main objects of this invention to compensate a device of the above type for the eflect which the walls of the device have upon the temperature of the air within the chamber.

A further object of the invention is to accomplish this compensating effect by means of a second chamber having an expansible fluid therein and in which the walls thereof are equally aflected by radiant heat so that the walls ofthe first chamber and the walls of the second chamber will affect their fluid equally. The invention further includes the feature of providing. a means responsive to difierence in pressure of the fluids in the two chambers so that the ei fect of the wall temperature of the second chamber will act on the differential pressure responsive means to compensate it for the eifect of the wall on the temperature of the fluid in the first chamber.

A still further object of the invention is to insert aheat absorbing means in the second, or compensating, chamber in order to assist the compensation of the .wall temperature effect on the first chamber. The invention also includes the feature of providing a means for adjusting the effect which the radiant heat has on theabsorbing means in the compensatingchamber in order that this device may be properly calibrated. The last named means may be in the form 01' an adjustable heat shield for shielding variable portions of the heat absorbing means in the compensating chamber.

Another object of the invention is to make the cular cross-section and then have the compensating chamber in the form of an annulus surrounding the first chamber.

Still another object of the invention is to place the second chamber immediately in front of the first chamber so that the face of the first chamber forms the rear wall of the second or compensating chamber and the radiant heat passes serially through said chambers, passing first through the compensating chamber and then through the first chamber. In such case 3. diaphragm is located at the rear of the first chamber for responding to the pressure therein, and .a passageway communicates or connects the opposite side of the diaphragm and the second chamber so that the diaphragm will respond to the difference in pressure between the two chambers.

These and other objects will readily become apparent to those who are skilled in the art as the following specification is read in the light of the accompanying drawing in which,-

Figure l is a front elevation of a first modification of my invention,

Figure 2 is a section taken along the line 2-2 of Figure 1, and

Figure 3 is a longitudinal sectional view of a modified form of my invention.

Referring now to Figures 1 and 2 of the drawing, the reference numeral 10 indicates a housing having a pair of concentric circular walls H and I2 forming a first open-ended cylindrical chamber l3 and a second annular open-ended chamber H which surrounds the chamber IS. A circular face plate- 15 closes the open end of the two chambers l3 and H. The face plate l5 must be made of some material which will transmit radiant heat so that it can pass into the chambers I3 and I4. -This face plate is P e y made of Lucite. Any other material which will transmit radiant heat such as glass or other plastics may be used if desired. For the purpose of convenience the housing 10 is also made of Lucitaands the housing II and face plate l5 are a fused togetheriu orderto make the two chambars 13 and J4 airtight.

The two chambersv I3 and ld-inust be filled g with a heat expansible fluid of some kind. In

thisparticularcase hydrogen is used,-. although many other fluids; such as air,-may be used if idesired. Located. within the chamber-- I3 is aheat absorbing means in the'form of a thin metal foil,,such as aluminum foil, the side facing the face plate if: being blackened in order that it may more. readily absorb the radiant heat passing through the. faceplate l5. .Themet-al foil is connected to thewall ll atthree different points indicated at l8 so that when'the hydrogen within the chamber I3. is heated bythe metal foil. as it absorbs the -radiant heat passing, intothe chamber 13,- the hydrogen may readily circulate ture.

A Ulube' 20 is connected one end to the interior of the chamber l3'and atthe other end to thechamber M. The U. portion of the tube carries a quantityof liquid such as colored water or mercury so that the liquid" will rise or fall in the two legs of the tube,depending upon the difaround] it so that. all of the hydrogen .in this. ;chamber.Will-rapidly come-to the same tempera:-

m calibrate the'device, means have been provided ference in pressure existing between the two chamber-s13 and. a

The operation of the device asdescribed thus .far should now -be apparent.- Assuming that there is no radiant heat striking theface plate l5,'the temperature of the hydrogen in the .two

' chambers l3 and M should be the same; and

1 asst-goo tensity of heat radiation in the same manner as a .will the effect of the faceplate I 5 and wall l l upon the temperature of the hydrogen in the chamber 13. Therefore, if-theseefiects are equal -and opposite then the indicating liquid 2| will move in direct accordance. with the intensity of the heat radiation passing into the chamber. l3

and. absorbed bythe metal foil l1.

One of the desirable features of the modification shown in Figures 1 and Z is that the; device can be calibrated after it has, once been set up. This is accomplished by so designing the two chambers I 3- and I4 that the efiectof the heat ,uponthe walls H and I2 is not quite sufficient to properly. compensate the device. The addi: tional compensation is obtained by the provision of a heat absorbing ring 2-5 mounted in the chamber M. This ring is made of some suitable material whichhas a substantial mass whose temperature will therefore lag behind the variations in heat radiations in the same manner as the walls H and l2 and the face plate l5; In order to forvarying the total area of the ring 25whi'ch the heat radiations may strike. This means is in the formyof an arcuate heat shield 26 which is .mounted upon a' bellows 21 and adjustedverti- Lcally' byrneans of a manually operable screw 28.

As the heat shield 26 is lowered, more and more of the ring 25- is subjected to the heat radiations passing through the plate l5, and as this heat shield is raised, it. cuts off more and more of the heat radiations. Ihis heat shield must necestherefore theliquid '2l should be at the same level in the two legs of the U tube 20. If radiant heat should nowstrike theface plate. i5, it will pass therethrough and into the chambers l3 and M where it: will rapidly be absorbed by the metal- 'foil l! which will immediately he'at the hydrogen in the chamber 13. This will cause an increase in pressure in'the chamber l3 and the liquid will sarily be made of some heat insulating material whichgwill not have any substantial effect upon the" temperature of the air in the chamber I4 be forceddownwardly in the leg 220i the U tube and upwardly. in the leg 2.3. The radiant heat I willnot only be absorbed by the me'talfoill1 butalso to aecertainextent by the face plate 15 and also bythewall ll. As H and I5 increase in temperature they will also have a certain heating effect upon the hydrogenin the chamber l3.

--'I-'his is .an undesirableefiect because the temperatures of the members H and l5lag consid- -'erablybehind the. changes in the intensity of the radiant heat. The metal foilfll has only a very slight mass and therefore its temperaturewill other thanthe eifect in. shielding-variable portions of the ring 25. In this manner the compensating effect of the chamber ld' may be varied suficiently to properly calibrate the device as-a whole after it has once been installed.

l I Referring now to Figure 3; a modified formof' my invention is shown. This modification in.-

fit together to form a unitary structuref.

. y the major axis of the ellipsoidso that the hydrovery closely follow the amount of radiant heatpassing through the jface plate l5. Itis there-- foredesired that the indicating liquid 2| should gen which issealed in the chamber may circulate freely. The cup shapedmember 34 having a face 35 is-insertedover thej twomembers 30 and 3|,

I move in the U tubein direct accordance with the amount of heat absorbed by the metal'foil l1 and communicated to the'hydrogen in the chamber l3 and therefore the efiect whichthe wall ll v and face plate. l5 have on the temperature of the hydrogen in the chamber l3 should 'be removed tensity of the heatradiation striking the face platel5..

'- In order to compensate for}ethe'effccti'of the wall II and fac plate l5 upon the temperature the face being spaced from the faceplate 3! and forming a chamber between the face 35- and the face plate 3]." This chamber' 36 is also filledwith hydrogen. Y

The .base member so is provided. with a diaphragm chamber inwhich a movable diaphragm if the liquid 2| is'to accurately indicate-the inof the hydrogen in the-chamber lI'l, -an'ec1ual and opposite. effect is produced in the chamber l4. Thus the radiant .heat will also heat that 31 is circumferentiall'y clamped against the base member 30 by meansofaplug" 38. 'Thecliambr' .65:'33-communicates with one side. of the diaphragm 4 31 through the passage 39. The other side of the diaphragm -31carries astem 40 whichextends through an opening in the plugmember 38.

- A closure-member 42 seats on the base member portion of the faceplate l5 which closes the chamber M as well as J2 and their temperat re will afiect the tempera-" ture of the hydrogen in the chamber M. This effect will lag behind the actual changes in ine wall ll andthe wall 30 and cooperates with the cup shaped member 34- to sealthe interior of the entire device from the external atmosphere. A cut-awayportion I 43 in the cup 34 connects the chamber 36 with that side oith diaphragm 31 which-carriesthe stem 40. Thus, the diaphragm 3lrespondsto .the

engagement with the stationary contact 43.

difference in the pressure between the chamber 33 and the chamber".

The closure member '42 carries a pair of stationary contacts 43 and 46 between which a flexi- I the two chambers.

In this modification, the radiant heat must I pass successively through the chamber 36 and chamber 33. For this reason the face plate 3| and the face 35 of the cup 34 must be made of some material which will transmit the heat radiation.. Preferably, the entire construction, that is the cup 34, face plate 3|, base 30 and closure member 42 are all made of Lucite so that they may be readily sealed together to form an air tight enclosure. It will be appreciated however that other plastics may be used to advantage if desired.

The operation of this device is substantially the same as the device shown in Figures 1 and 2. When no heat radiation is striking the face 35, the hydrogen in the chambers 36 and 33 is at one temperature, th pressures across the diaphragm 31 are equal, and this diaphragm is therefore in a position in which th contact blade 41 is in engagement with the stationary contact 45. As heat radiations strike the face 35 and pass into the chamber 33, they will be absorbed by the blackened surface of the metal foil 32 which will thus cause heating of the hydrogen in the chamber 33. This will cause an increase inthe pressure therein, and when the intensity of the heat radiation striking the face 35 has increased sufliciently, this pressure will cause the diaphragm 31 to expand sufllciently to separate the contact blade 41 from the stationary contact 45. As in the case of the modification shown in Figures 1 and 2, the walls of the chamber 33 formed by the face plate 3| and the base 30 will also be heated to a certain extent by the heat radiations. The temperature of these-walls will obviously affect the temperature of the hydrogen in the chamber 33 and as this effect lags considerably behind the changes in intensity of the heat radiations it is an undesirable effect and therefore should be compensated. This compensation is attained in this modification by means of the cup 34 and chamber 36. The cup- 34 is so designed that it will absorb sufficient heat to increase the pressure of the hydrogen in the chamber 36 in the same amount that the face plate 3| and base 30 will increase the pressure of the hydrogen in the chamber 33. These two metal foil 32.

As the intensity of the radiant heat increases, it will be apparent that the difference in pressure between the chambers 33 and 33 will increase with the result that the diaphragm 31 will eventually move the resilient contact blade 41 over into It is therefore apparent that as long as the intensity of the heat radiations is within a predetermined range, the resilient contact 41 will be out of engagement with both of the contacts 45 and 43, but that when the intensity of these heat radiations is below a predetermined range the blade 41 will engage contact 45 while if the intensity goes above this range the blade 41 will engage the contact 46.- This device willtherefore 'close one circuit when the intensity of the heat radiations is'above a predetermined range and close another circuit when the heat radiation intensity is below a certain range.

The main advantage of this device over the device shown in Figures 1 and 2 is that it is a more compact unit and also a smaller unit. This compactness is accomplished by causing the heat radiations to pass successively through the two chambers instead of arranging these chambers so that the heat radiations strike them simulta- 1 neously. In order to get the proper compensating e'lfect, it is only necessary to design the cup 34 so that the heating of this cup will have the same effect on the pressure in the chamber 36 as the heating of the face plate3| and base 30 have on the temperature and pressure of the hydrogen in the chamber 33.

It will be apparent also that the two chambers of both modifications of my invention, when acting in opposition as shown, compensate each other for variations in ambient temperature. Thus variations in ambient temperature will have no effect upon the liquid in the U tube of Figures 1 and 2 or upon the diaphragm 31 of v Figure 3.

1 As many changes and modifications of this invention will doubtless occur to those who are skilled in the art, I'wish it to be understood that I intend to be limited by the scope of the appended claims and not by the specific embodi- 'ments which have been disclosed herein only for the purposes of illustration.

'1 claim as my invention:

1. A radiant heat responsive device comprising in combination, housing means having walls forming a pair of sealed pressure chambers, a heat expansible fluid in said chambers, means responsive to the difference in pressure of the fluid in said chambers, said pressure responsive means sealing said chambers with respect to each other, said housing means having a portion capable of transmitting radiant heat therethrough and into said first chamber, means in said first chamber absorbing the radiant heat for heating the fluid therein, the walls of said first chamber .absorbing a, certain amount of heat thus producing an additional effect on the temperature of the fluid therein, the walls of said second chamber being designed to absorb suflicient heat to raise the temperature of the fluid. therein an amount to just balance said additional eifect on the fluid in said first chamber, at least one of said walls being common to both chambers for heating the fluid therein, whereby said pressure responsive means responds at all times .to the amount of radiant heat striking said housing and is unaffected by the changes in temperature of the walls of said housing.

7 2. A radiant heat responsive device comprising in combination, housing means having walls forming a pair of sealed pressure chambers, a heat expansible fluid in said chambers, means responsive to the difference in pressure of the fluid in said chambers, said pressure responsive means normally sealing said chambers with respect to each other, said housing means 1: Wing a portion capable of transmitting radiant heat therethrough into said flrst chamber, means in said first chamberabsorbingthe radiant heat for heating the fluid therein, the walls 'of said first chamber absorbing a certain amount of heat thus producing an additionalleffect on the. temperature of the fluid therein, said housing heat into said second chamber, means within said second chamber for absorbing radiant heat for heating the fluid therein, the walls of said second chamber and the heat absorbing means in said second chamberbein'g designed to como pensate said pressure responsive means for 'changes in pressure due to said additional effect upon the temperature oi the fluid in said first chamber, at least one of said wallsbeing common to both chambers for heating the fluid therein.

3. A radiant heat responsive device comprising in combination, housing means having walls a forming a pair of sealed. pressure chambers, a

heatexp'ansiblefluid in said" chambers, means ass fio V a amounts of said heat absorbing meansfromsaid 1 "heat radiations. i

' having a, portion capable of transmitting radiant heat radiations striking said housing, and means responsive to the difi'erence in pressure of the fluid in said chamber, said housing means having a portion capable of transmitting radiant heat therethrough and into said first chamber;

- means in said first =chamber'absorbing the radiant heat for heating the fluid therein, the 'walls of said first chamber absorbing a certain amount I of heat thus producing an additional eifect on the temperature of the'fluid therein, said housing having a portion capable of transmittingradiant heat into said second chamber, means within .said second chamber for {absorbing ra-l diant heat for heating the fluid therein, the walls of said second chamber and the heat absorbing means in said second chamber .being'd'es-igned to compensate said pressure responsive means for changes in pressure due to said additional effect upon the temperature of the fluid ins aid first chamber, and means for adjusting the proportional amount. of radiant heatfabsorbed by the absorbing means in said second chamber whereby the compensating efiect of said second chamber may be properly adjusted. 7

4. A radiant heatresponsive device comprisforming afpair of sealed pressure chambers, a

heat expansible fluid in said chambers, means within saidsecond chamber for absorbing radiant heat for heating the fluid therein, the

walls of-said second chamber and the heat ab sorbing means in said second chamber being designed to compensate said pressure responsive means for changes inpressure due to said addi tional effect upon the temperature of the fluidins'aid first chamber, and'means for adjusting I the proportional amount of radiantheat absorbed by the absorbing means in said second chamber whereby the compensating effect of 4 said second chamber may be properly adjusted,.

said last named means comprising a heat shield of low heat capacity for shielding various ing in combination, housing means having walls 5. A radiant heat responsive device comprising a housing having walls forming a sealed 'cha m- V her, a portion or said housing being capable of.

transmitting radiantrheat .therethrough to the interior of said chamber, a heat expansible fluid, in said chamber, absorbing radiant heat.

passing'f'throughsaid housingfor heating said fluid an amount dependent upon the intensity of j heatradiations striking said housing-the walls ofjsaid housing also absorbing radiant heat for producing an additional heating effect upon said fluid, means responsive to the pressure in said chamber, means automatically producing a-prese screen said pressureresponsive means which is opposite and substantially'equal to the pressure change in said fluid resulting from said additional heating 'efiect, whereby the position assumed by said pressure responsive means will be at all times. dependent solely upon the intensity of the for manually adjusting the eflect of said auto-- inatic means upon saidpressure; responsive 6. Aradiant heat responsive device comprising in combination, housing means having walls forming apair of sealed pressure chambers, a

heat expansible fluid in saidjchambers, a-diaphragm sealing said chambers with respect toeach other and movable upon variations iii the pressure difierence between'th fluid in the'two I chambers, said housing means'having aportion 4 capable of transmitting radiant heat 7 therethrough and into said first chamber, 'means in said first chamber absorbing the radiant heat for.

' heating the fluid therein, thewalls of said first chamber absorbing a certain amount ofheat thus producing an additional efiect on the temperature of-the fluid therein, the walls of said second; chamber beingdes'igned toabsorb suflicient heat to raise the temperature bfthe fluid therein an amount to just balance'said additional-efiect' on f the fluid in said first chamber, whereby said dia phragm is .positionedat all-times. accordance .with the amount-of radiant heat striking said housingand is independent of the temperature 1 of the walls of said housing, and switch means operated by said diaphragm when the intensity of the heat radiations striking said housing reach a predetermined value,

, in combination, a cup shaped housing forming a 7.7 A radiant heat responsive device comprising first chamber having a wall portion at one side capable of transmitting radiant heat within said chamber, means forming an annular chamber surrounding said first chamber, said second chamber having a' wall portion capable of trans- I second chamber tending to balance the pressure v mitting radiant heat within said second chamber,

the wall portion fer said second chamber being on the same side as the wall portion of said first chamber, a heat expansible fluid in said chambers, means responsive to the difierence in pressure in said two chambers, and means in said first chamber for absorbing radiant heat passing through its wall portion and the fluid therein, the wall portions of both of said chambers absorbing radiant heat and therefore affecting the temperature and pressure of the fluid in their respective chambers, thepressure in said in said first chamber.-

8. A radiant heat responsive device comprising in combination, a cup shaped housing forming. a

V first chamber having a wall portion atone side capable of transmitting radiant heat within said chamber, means forming an annular chamber surrounding said first chamber, said second chamber having a wall portion capable of transmitting radiant heat within said second chamber, the wall portion for said second chamber being on the same side as the wall portion of said first chamber, a heat expansible fluid in said chambers, means responsive to the difference in pressure in said two chambers, means in said first chamber for absorbing radiant heat passing through its wall portion and expanding the fluid therein, the wall portions of both of said chambers absorbing radiant heat and therefore af-' fecting the temperature and pressure of the fluid in their respective chambers, and means in said second chamber for absorbing radiant heat and heating the fluid therein, said last named means being so chosen that its eflfcct plus the efiect of the walls of said second chamber upon the fluid therein compensate for the effect of the walls of said first chamber upon the fluid therein.

9. A radiant heat responsive device comprising in combination, a cup shaped housing forming a first chamber having a wall portion at one side capable of transmitting radiant heat within said chamber, means forming an annular chamber surrounding said first chamber, said second chamber having a wall portion capable of transmitting radiant heat'within said second chamber, the wall portion for said second chamber being on the same side as the wall portion of said first chamber, a-he'at expansible fluid in said chambers. means responsive to the difierence in pressure in said two chambers, means in said first chamber for absorbing radiant heat passing through its wall portion and expanding the fluid therein, the wall portions of both of said chambers absorbing radiant heat and therefore affecting the temperature and pressure of the fluid in their respective chambers, means in said second chamber for absorbing radiant heat andheating the fluid therein, said last named means being so chosen that its effect plus the efiect oi the walls i. said second chamber upon the fluid therein compensate for the effect of the walls 01' said first chamber upon the fluid therein, and means for adjusting the proportion of radiant heat absorbed by the absorbing mean in said second chamber whereby the compensating eflect of said second chamber upon said first may be properly 10. .A radiantheat responsive device comprising in combination, a cup shaped housing forming a first chamber having a wall portion at one side capable pi transmitting radiant heat within said chamber; means forming an annular cham-' ber surrounding said first chamber, said second chamber having a wall portion capable of trans- ?Iiitting radiant heat within said second chamber,

e on thevsame j'side asthe wall portion of said first chamber, a heat expansible fluid in said chambers, means responsive to the difierence in pressure in said two chambers, means in said first chamber for absorbing radiant heat passing through its wall portionand expanding the fiuid therein, the wall portions'of both of said chambers absorbing radiant heat'and therefore affecting the temper-' ature and pressure of the fluid in their respective chambers, and means in said second chamber for absorbing radiant heat and heating the fluid therein, said last named means being so chosen thatits efiect plus the direct of the walls of said wall portion for said second chamber beingsecond chamber upon the fluid therein compensate for the effect of the walls of said first chamber upon the fluid therein, a heat shield for shielding a portion of said last mentioned means 5 (from the radiant heat passing into said second chamber, and means for adjusting said shield to vary its position and hence the area of the means which it shields.

11. A radiant heat responsive device comprisl0 ing in combination, housing means having walls forming first and second chambers, said first chamber being located behind of said second chamber, portions of said walls being capable of transmitting radiant heat and being so located that radiant heat may pass through said second chamber and into said first chamber, a heat expansible fluid in both of said chambers, means responsive to the difierence between the pressures of the fluid in said chambers, and means in said first chamber for absorbing radiant heat for heating and expanding the fluid therein, said radiant heat also heating the walls of said first and second chambers which heat and expand the fluid in said chambers, the position and mass of said walls being such that they afiect the fluid in said two chambers equally.

12. A radiant heat responsive device comprising in combination, wall means comprising a base and a face plate forming a chamber, a second face plate cooperating with said first face plate to form a second chamber, said face plates being capable of transmitting radiant heat whereby radiant heat may pass through said second chamber and into said first chamber, a heat expansible 5 fluid in said chambers, means in said first chamber absorbing radiant heat passing into said first chamber and heating and expanding the fluid therein, and means responsive to the diflerence between the pressures oi the fluid in said chambers, said radiant heat being absorbed to a cer tain extent by the walls of said chambers and aflecting the temperature of the fluid therein, said last named effects being substantially the same whereby said second chamber will compensate the first for such effects.

13. A radiant heat responsive device comprising in combination, wall means comprising a base and a face plate forming a chamber, a second face plate cooperating with said first face plate to form a' second chamber, said face plates being capable of transmitting radiant heat whereby radiant heat may pass through said second chamber and into said first chamber, a heat expansible fluid in said chambers, means in said first chamber absorbing radiant heat passing into said first chamber and heating and expanding the fluid therein, means sealing said first chamber including a diaphragm subject at one side to the pressure therein, means affording communication between said second chamber and the opposite side of said diaphragm whereby said diaphragm responds to the difference in pressure in the fluid in said chambers, said diaphragm being so located with respect to said chambers as not to interfere with the D 8- sage of radiant heat therethrough, said walls of said two chambers being so designed as to absorb radiantheat in amounts which will expand the fluid in said chambers to produce substantially equal effects upon said diaphragm whereby 70 said diaphragm responds only to the amoimt of heat absorbed by said absorbing means in said first chamber.

SIEGFRJED G. ISSERSI'ED'I'. 

